Pulse measuring instrument

ABSTRACT

A pulse wave measuring apparatus including a semiconductor substrate having a pressure-sensing device on a main surface and a protection member with an accommodation space therein for accommodating the semiconductor substrate detects a pulse wave of an artery located in a living body by pressing the semiconductor substrate against the body. A wall surface of the protection member that forms the accommodation space is arranged such that an air chamber is interposed between the wall surface and an end surface of the semiconductor substrate that is exposed to air. A pulse wave measuring apparatus of this structure allows accurate and stable measurement of the pulse wave.

TECHNICAL FIELD

The present invention relates to a pulse wave measuring apparatus, andmore particularly to a pressurization-type pulse wave measuringapparatus measuring a pulse wave by pressing a substrate includingpressure-sensing means against a living body.

BACKGROUND ART

In general, a pressurization-type pressure measuring apparatus formeasuring contact pressure with respect to a target object by pressingthe apparatus against the target object has been known. An applicationexample of such a pressurization-type pressure measuring apparatusincludes a pulse wave measuring apparatus. A pulse wave measuringapparatus is used for measuring a pulse wave by pressing a substratehaving pressure-sensing means against a body surface in order to measurea pulse wave generated in an artery located in a relatively shallowportion under the skin of the living body. In order to know medicalcondition of a subject, it is extremely important to measure a pulsewave of the subject, using such a pulse wave measuring apparatus.

In the pressurization-type pulse wave measuring apparatus, asemiconductor pressure sensor utilizing a strain gauge or a diaphragm iscommonly used as the pressure-sensing means. In such a case, thesubstrate is arranged such that the pressure-sensing means for detectingthe pulse wave is located on a surface of a housing attached to theliving body. For example, Japanese Patent Laying-Open No. 4-67839relates to such a pressurization-type pulse wave measuring apparatus.

FIG. 33 is a schematic partial cross-sectional view of the pulse wavemeasuring apparatus disclosed in the above publication. As shown in FIG.33, the pulse wave measuring apparatus disclosed in this publicationincludes a pressure-sensing portion 130 on the surface of the housing.Pressure-sensing portion 130 includes a semiconductor substrate 101having a pressure-sensing device formed on a main surface, a supportmember 109 supporting semiconductor substrate 101, and a protectionmember 112 fixing support member 109. A circuit board 126 provided witha processing circuit processing a signal output from thepressure-sensing device is arranged in the housing. A flexible line 118establishes electrical connection between semiconductor substrate 101having the pressure-sensing device formed and circuit board 126. Inorder to protect the pressure-sensing device, pressure-sensing portion130 is sealed by silicon rubber 123. In other words, silicon rubber 123covers an upper surface and an end surface of semiconductor substrate101 having the pressure-sensing device formed.

On the other hand, the pulse wave measuring apparatus of a structuredescribed above suffers from a variety of problems as below.

First, volume fluctuation may take place in the silicon rubber coveringa periphery of the semiconductor substrate due to variation in anambient temperature and heat transfer from the body surface. As thevolume fluctuation acts as a stress on the semiconductor substrate,there is a possibility that the stress acts on the pressure-sensingdevice and that resultant noise is superposed on the detected pulsewave. Such volume fluctuation of the silicon rubber occurs also byabsorption by the silicon rubber of perspiration on the body surface ofthe subject. In addition, if a void is present in the silicon rubber orbetween the semiconductor substrate and the silicon rubber, volumefluctuation of the void itself is further produced in addition to thevolume fluctuation of the silicon rubber, whereby the stress is appliedto the semiconductor substrate in a complicated manner. Consequently,accurate measurement of the pulse wave becomes more difficult.

Secondly, deformation of the semiconductor substrate tends to besuppressed by the silicon rubber. A force due to a pressure produced inaccordance with pulsation is applied to the semiconductor substrate in adirection orthogonal to a pressure-sensing surface. When such a force isapplied, the semiconductor substrate attempts to deform slightly so asto extend in a lateral direction. On the other hand, as the end surfaceof the semiconductor substrate is sealed by the silicon rubber in thestructure above, deformation in the lateral direction of thesemiconductor substrate is suppressed. Accordingly, stress distributionin the semiconductor substrate becomes complicated, and resultant noisemay be superposed on the pulse wave detected by the pressure-sensingdevice.

Thirdly, skin tension may be applied to the pressure-sensing surface. Inthe following, this problem will be described in detail with referenceto the drawing.

FIG. 34 is a schematic diagram pointing out the problem in theconventional pulse wave measuring apparatus. As shown in FIG. 34, in thepressurization-type pulse wave measuring apparatus, pressure-sensingportion 130 is pressed against a body surface 40 (in a direction shownwith an arrow A in the figure) so as to measure the pulse wave. When apressure-sensing surface 102 is flat, the skin tension acts in adirection parallel to the pressure-sensing surface, and therefore, theskin tension does not affect the pressure-sensing device.

In the pulse wave measuring apparatus disclosed in the publicationabove, however, as shown in FIG. 33, flexible line 118 for transmittinga signal output from the pressure-sensing device to circuit board 126 isconnected to the main surface of semiconductor substrate 101.Accordingly, on the main surface of semiconductor substrate 101, thereexist a region carrying silicon rubber 123 alone and a region carryingboth silicon rubber 123 and flexible line 118.

Flexible line 118 has elasticity significantly poorer than siliconrubber 123. Therefore, in the pulse wave measuring apparatus disclosedin the publication above, as shown in FIG. 34, such poor elasticity iscomparable to a condition in which the pressure-sensing surface hasirregularities. Here, as shown in FIG. 34, the skin tension is appliedin a direction orthogonal to pressure-sensing surface 102 (in adirection shown with an arrow B in the figure) to the skin directlyunder pressure-sensing surface 102. As a result, a component of force ofthe skin tension acts on pressure-sensing surface 102. Then, stressdistribution in semiconductor substrate 101 becomes complicated, andresultant noise may be superposed on the detected pulse wave.

As described above, in the pulse wave measuring apparatus disclosed inthe publication above, a variety of stresses act on the semiconductorsubstrate, and the resultant noise is superposed on the detected pulsewave. Consequently, it has been difficult to measure the pulse wave withhigh accuracy in a stable manner.

On the other hand, in order to achieve sufficient protection effect ofthe silicon rubber against the stress from a side surface to thesemiconductor substrate, the silicon rubber for sealing should have asufficiently large thickness. Larger thickness of the silicon rubber,however, leads to a larger size of the pulse wave measuring apparatus,which results in difficulty in achieving a shape fitting to the livingbody.

As described above, in the pulse wave measuring apparatus disclosed inthe publication above, the pressure-sensing portion is disadvantageouslymade larger in order to ensure an effect to protect the pressure-sensingdevice, and it has been difficult to provide a compact andhigh-performance pulse wave measuring apparatus.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a pulse wave measuringapparatus capable of accurate and stable measurement of a pulse wave. Inaddition, it is another object of the present invention to provide acompact and high-performance pulse wave measuring apparatus.

A pulse wave measuring apparatus according to a first aspect of thepresent invention includes a substrate having pressure-sensing means ona main surface, and a protection member having an accommodation spaceaccommodating the substrate. The pulse wave measuring apparatus servesto measure a pulse wave by pressing the substrate against a living body.In the pulse wave measuring apparatus according to the first aspect ofthe present invention, a wall surface of the protection member formingthe accommodation space is arranged such that an air chamber isinterposed between the wall surface and an end surface of the substrate.

In this manner, the wall surface of the protection member forming theaccommodation space and the end surface of the substrate are arrangedspaced apart from each other, so that the end surface of the substratehaving the pressure-sensing means is surrounded by the air chamber. Assuch, even if variation in the ambient temperature or heat transfer fromthe body surface takes place, stress distribution in the substrate willnot be complicated. In other words, as the end surface of the substrateis surrounded by the air chamber, stress caused by volume fluctuation ofanother member when the end surface of the substrate is covered byanother member will not be applied to the substrate, whereby accurateand stable measurement of the pulse wave is allowed.

In addition, as the end surface of the substrate is surrounded by theair chamber, deformation of the substrate in the lateral directioncaused by pressurization of the substrate against the subject is nolonger suppressed. Accordingly, stress distribution in the substratewill not be complicated, and consequently, accurate and stablemeasurement of the pulse wave is allowed.

Moreover, by disposing the substrate in the accommodation space in theprotection member, protection of the substrate by the protection memberis ensured. Therefore, a compact and high-performance pulse wavemeasuring apparatus can be provided.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the air chamber is provided around anentire perimeter of the substrate, for example. In this manner, theentire end surface of the substrate is exposed and faces the airchamber, thereby significantly reducing the stress applied to thesubstrate. Consequently, the pulse wave can be measured with very highaccuracy.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the air chamber is open toatmosphere, for example. When the air chamber is open to atmosphere, airpressure in the air chamber can constantly be maintained to anatmospheric pressure. Accordingly, the stress applied to the substrateis significantly reduced.

The pulse wave measuring apparatus according to the first aspect of thepresent invention may further include a circuit board processing asignal, and a flexible line transmitting a signal output from thepressure-sensing means to the circuit board. In such a case, theflexible line preferably includes a fixed portion, a connection portion,and a loosened portion. Here, the fixed portion refers to a portion ofthe flexible line fixed to the protection member, and the connectionportion refers to a portion thereof connected to the substrate. Theloosened portion is preferably located between the fixed portion and theconnection portion. In this manner, by providing the loosened portion inthe flexible line, the loosened portion mitigates the stress even whenvolume fluctuation takes place in the flexible line, therebysignificantly reducing the stress applied to the substrate.Consequently, accurate and stable measurement of the pulse wave isallowed.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the loosened portion is locatedinside the air chamber, for example. When the loosened portion of theflexible line is located in the air chamber, a larger size of theapparatus due to provision of the loosened portion is avoided, and acompact and high-performance pulse wave measuring apparatus can beprovided.

The pulse wave measuring apparatus according to the first aspect of thepresent invention may further include a circuit board processing asignal, and a flexible line transmitting a signal output from thepressure-sensing means to the circuit board. In such a case, theflexible line preferably includes a fixed portion and a connectionportion. Here, the fixed portion refers to a portion of the flexibleline fixed to the protection member, and the connection portion refersto a portion thereof connected to the substrate. In addition,preferably, a portion having rigidity different from that of anotherportion of the flexible line is located between the fixed portion andthe connection portion of the flexible line. By providing the portionhaving rigidity different from that of another portion in the flexibleline, the stress is mitigated by this portion even when volumefluctuation takes place in the flexible line, whereby the stress appliedto the substrate is significantly reduced. Consequently, accurate andstable measurement of the pulse wave is allowed. Here, in order toprovide a portion having rigidity different from that of another portionin the flexible line, a coating of the flexible line is partiallyremoved or its thickness is partially made smaller.

Preferably, the pulse wave measuring apparatus according to the firstaspect of the present invention further includes a protection filmcovering the main surface of the substrate and the air chamber, andattachment means for fastening a peripheral portion of the protectionfilm around an outer circumferential wall of the protection member forattachment. In this manner, by providing the protection film coveringthe main surface of the substrate, breakage of the pressure-sensingmeans is prevented. In addition, when the protection film is fastenedaround the outer circumferential wall of the protection member using theattachment means, detachment of the protection film from the protectionmember is prevented.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the protection member has asubstantially circular outer shape when viewed from a directionorthogonal to the main surface of the substrate, and the attachmentmeans is an O ring, for example. When the protection member has asubstantially circular outer shape, the protection film can readily beattached to the protection member using the O ring.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the outer circumferential wall of theprotection member has a concave fitting portion fitting to the innerportion of the O ring on an entire circumference, and an outer portionof the O ring projects from the outer circumferential wall of theprotection member, for example. In this manner, the concave fittingportion is provided on the outer circumferential wall of the protectionmember, and the O ring is fitted to the concave fitting portion, therebyensuring prevention of detachment of the protection film. In addition,as the outer portion of the O ring projects from the outercircumferential wall of the protection member, a sealed system includingthe pressure-sensing surface can readily be structured by attaching ameasurement jig of a cylindrical shape with a bottom to the O ring froma surface side of the substrate so as to achieve intimate contact.Therefore, output characteristics of the pressure-sensing device canreadily be measured.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the protection film and theattachment means are integrally formed, for example. By integrallyforming the protection film and the attachment means, the number ofparts can be reduced, which leads to facilitated assembly operation andreduction in manufacturing cost.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the protection film has a collarportion in its peripheral portion, for example. By providing the collarportion in the protection film, the protection film can be attached tothe protection member by gripping the collar portion, whereby theassembly operation is facilitated.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, for example, the protection memberincludes an inner frame body containing the accommodation space and anouter frame body fitted to the inner frame body so as to enclose anouter wall of the inner frame body. Here, the outer frame bodypreferably has a protection film portion covering the main surface ofthe pressure-sensing means and the air chamber, and a projected portionprovided on an entire circumference of its outer wall. By integrallyforming the protection film and the inner frame body, the number ofparts can be reduced, which leads to facilitated assembly operation andreduction in manufacturing cost. In addition, by providing the projectedportion on the outer circumferential wall of the outer frame body, asealed system including the pressure-sensing surface can readily bestructured by attaching a measurement jig of a cylindrical shape with abottom to the projected portion from a surface side of the substrate soas to achieve intimate contact. Therefore, the output characteristic ofthe pressure-sensing device can readily be measured.

The pulse wave measuring apparatus according to the first aspect of thepresent invention may further include a circuit board processing asignal, and a flexible line transmitting a signal output from thepressure-sensing means to the circuit board. In such a case, preferably,the protection member includes an inner frame body containing theaccommodation space and an outer frame body fitted to the inner framebody so as to enclose an outer wall of the inner frame body, and theflexible line is inserted between the inner frame body and the outerframe body. The flexible line is inserted through the protection memberinstead of being arranged along the outer wall of the protection member,so that detachment of the flexible line can be prevented.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the outer frame body has anoverhanging portion provided so as to project from an inner surface ofthe outer frame body and facing, with a distance, a perimeter of anaccommodation space forming surface of the inner frame body where theaccommodation space is formed, for example. The flexible line insertedbetween the inner frame body and the outer frame body is preferablyprotected by the overhanging portion. By providing the overhangingportion protecting the flexible line in the outer frame body,concentration on the flexible line of the pressurization force caused bypressing the pressure-sensing portion against the living body can beavoided, thereby eliminating a possibility of disconnection of theflexible line.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the protection member is formed witha conductive material. Here, preferably, the protection member iselectrically connected to a ground potential. According to such astructure, the pressure-sensing means is less susceptible to staticelectricity or noise from electric or magnetic field. Therefore,accurate and stable measurement of the pulse wave is allowed.

The pulse wave measuring apparatus according to the first aspect of thepresent invention may further include a circuit board processing asignal, and a flexible line transmitting a signal output from thepressure-sensing means to the circuit board. Here, preferably, theprotection member is electrically connected to the ground potential bymeans of the flexible line. When the flexible line including a signalline transmitting a signal output from the pressure-sensing means alsoincludes a ground line connecting the protection member to the ground,the number of parts can be reduced, thereby attaining facilitatedassembly operation and reduction in manufacturing cost.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the protection member is formed witha metal material or a ceramic material, for example. In this manner, asheat produced in the pressure-sensing means is effectively dissipatedthrough the protection member, the pulse wave measuring apparatusexcellent in safety can be provided.

In the pulse wave measuring apparatus according to the first aspect ofthe present invention, preferably, the protection member has a pluralityof small irregularities on its surface, for example. In this manner, asa surface area of the protection member is increased, heat produced inthe pressure-sensing means can effectively be dissipated.

A pulse wave measuring apparatus according to a second aspect of thepresent invention serves to measure a pulse wave by pressing against aliving body a substrate having pressure-sensing means on a main surface.The substrate has a groove around the pressure-sensing means.

In this manner, the groove is provided on the surface of the substratearound the pressure-sensing means so as to implement a thin portion.Then, the stress applied to the end portion of the substrate can beabsorbed by the thin portion, and the stress applied to thepressure-sensing means can be reduced. As a result, accurate and stablemeasurement of the pulse wave is allowed. In addition, as the largersize of the pressure-sensing portion is avoided, a compact andhigh-performance pulse wave measuring apparatus can be provided.

The pulse wave measuring apparatus according to the second aspect of thepresent invention may further include a protection member protecting thesubstrate, a circuit board processing a signal, and a flexible linetransmitting a signal output from the pressure-sensing means to thecircuit board. In such a case, the flexible line preferably includes afixed portion, a connection portion, and a loosened portion. Here, thefixed portion refers to a portion of the flexible line fixed to theprotection member, and the connection portion refers to a portionthereof connected to the substrate. The loosened portion is preferablylocated between the fixed portion and the connection portion. In thismanner, by providing the loosened portion in the flexible line, theloosened portion mitigates the stress even when volume fluctuation takesplace in the flexible line, thereby significantly reducing the stressapplied to the substrate. Consequently, the pulse wave can be measuredwith high accuracy in a stable manner.

The pulse wave measuring apparatus according to the second aspect of thepresent invention may further include a protection member protecting thesubstrate, a circuit board processing a signal, and a flexible linetransmitting a signal output from the pressure-sensing means to thecircuit board. In such a case, the flexible line preferably includes afixed portion and a connection portion. Here, the fixed portion refersto a portion of the flexible line fixed to the protection member, andthe connection portion refers to a portion thereof connected to thesubstrate. In addition, preferably, a portion having rigidity differentfrom that of another portion of the flexible line is located between thefixed portion and the connection portion of the flexible line. Byproviding the portion having rigidity different from that of anotherportion in the flexible line, this portion serves to mitigate the stresseven when volume fluctuation takes place in the flexible line, wherebythe stress applied to the substrate can significantly be reduced.Consequently, accurate and stable measurement of the pulse wave isallowed. Here, in order to provide a portion having rigidity differentfrom that of another portion in the flexible line, a coating of theflexible line is partially removed or its thickness is partially madesmaller.

A pulse wave measuring apparatus according to a third aspect of thepresent invention includes a substrate having pressure-sensing means ona main surface, a circuit board processing a signal, and a flexible linetransmitting a signal output from the pressure-sensing means to thecircuit board. The pulse wave measuring apparatus serves to measure apulse wave by pressing the substrate against a living body. In the pulsewave measuring apparatus according to the third aspect of the presentinvention, the substrate has a connection electrode portion connected tothe flexible line, in a position lower than the main surface.

In this manner, by providing the connection electrode portion in aposition lower than the main surface of the substrate, a degree ofprojection of the flexible line from the main surface of the substrateis suppressed by a distance of lowering. As a result, irregularity onthe main surface of the substrate is suppressed, a component of force ofthe skin tension acting on the pressure-sensing surface is made smaller,and accurate and stable measurement of the pulse wave is allowed.

In the pulse wave measuring apparatus according to the third aspect ofthe present invention, preferably, the substrate has a stepped-downportion on its main surface, and the stepped-down portion has theconnection electrode portion formed thereon, for example. As to aspecific structure for providing the connection electrode portion in aposition lower than the main surface of the substrate, it is possiblethat the stepped-down portion is provided on the main surface of thesubstrate, and the connection electrode portion is formed on thestepped-down portion, as described above. In this manner, a degree ofprojection of the flexible line from the main surface of the substrateis suppressed by a distance of lowering. As a result, a component offorce of the skin tension acting on the pressure-sensing surface is madesmaller, and accurate and stable measurement of the pulse wave isallowed.

In the pulse wave measuring apparatus according to the third aspect ofthe present invention, preferably, an upper surface of the flexible linelocated on a side opposite to the connection electrode portion on thestepped-down portion and the main surface of the substrate are locatedon an identical plane, for example. In this manner, when the uppersurface of the flexible line and the main surface of the substrate, thatis, the pressure-sensing surface, are located on an identical plane, theskin tension no longer affects the pressure-sensing surface, andaccurate and stable measurement of the pulse wave is allowed.

In the pulse wave measuring apparatus according to the third aspect ofthe present invention, preferably, a spacer member is arranged on theupper surface of the flexible line, and an upper surface of the spacermember located on a side opposite to the flexible line and the mainsurface of the substrate are located on an identical plane, for example.In this manner, a contact portion with the body surface can be made flatby means of the spacer member.

In the pulse wave measuring apparatus according to the third aspect ofthe present invention, preferably, the connection electrode portion isformed on a back surface of the substrate, for example. As to anotherspecific structure for providing the connection electrode portion in aposition lower than the main surface of the substrate, it is possiblethat the connection electrode portion is provided on the back surface ofthe substrate as described above. In order to form the connectionelectrode portion on the back surface of the substrate, for example, itis possible to provide a through hole in the substrate so as to form aconnection contact therein. In this manner, as the flexible lineconnected to the substrate is no longer located on the main surface ofthe substrate, a portion of the pressure-sensing portion being incontact with the body surface can be made flat, and accurate and stablemeasurement of the pulse wave is allowed.

The pulse wave measuring apparatus according to the third aspect of thepresent invention may further include a protection member protecting thesubstrate, a circuit board processing a signal, and a flexible linetransmitting a signal output from the pressure-sensing means to thecircuit board. In such a case, the flexible line preferably includes afixed portion, a connection portion, and a loosened portion. Here, thefixed portion refers to a portion of the flexible line fixed to theprotection member, and the connection portion refers to a portionthereof connected to the substrate. The loosened portion is preferablylocated between the fixed portion and the connection portion. In thismanner, by providing the loosened portion in the flexible line, theloosened portion mitigates the stress even when volume fluctuation takesplace in the flexible line, thereby significantly reducing the stressapplied on the substrate. Consequently, accurate and stable measurementof the pulse wave is allowed.

The pulse wave measuring apparatus according to the third aspect of thepresent invention may further include a protection member protecting thesubstrate, a circuit board processing a signal, and a flexible linetransmitting a signal output from the pressure-sensing means to thecircuit board. In such a case, the flexible line preferably includes afixed portion and a connection portion. Here, the fixed portion refersto a portion of the flexible line fixed to the protection member, andthe connection portion refers to a portion thereof connected to thesubstrate. In addition, preferably, a portion having rigidity differentfrom that of another portion of the flexible line is located between thefixed portion and the connection portion of the flexible line. Byproviding the portion having rigidity different from that of anotherportion in the flexible line, this portion serves to mitigate the stresseven when volume fluctuation takes place in the flexible line, wherebythe stress applied to the substrate can significantly be reduced.Consequently, accurate and stable measurement of the pulse wave isallowed. Here, in order to provide a portion having rigidity differentfrom that of another portion in the flexible line, a coating of theflexible line is partially removed or its thickness is partially madesmaller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a pulse wave measuringapparatus in Embodiment 1 of the present invention.

FIG. 2A is a schematic perspective view of a housing portion of thepulse wave measuring apparatus in Embodiment 1 of the present invention.

FIG. 2B is a schematic bottom view of the housing portion of the pulsewave measuring apparatus in Embodiment 1 of the present invention.

FIG. 3A is a schematic diagram illustrating a pressurization mechanismof the pulse wave measuring apparatus in Embodiment 1 of the presentinvention, before measurement.

FIG. 3B is a schematic diagram illustrating the pressurization mechanismof the pulse wave measuring apparatus in Embodiment 1 of the presentinvention, during measurement.

FIG. 4 is a schematic cross-sectional view of a structure of apressure-sensing portion of the pulse wave measuring apparatus inEmbodiment 1 of the present invention.

FIG. 5 is an enlarged cross-sectional view of the pressure-sensingportion of the pulse wave measuring apparatus shown in FIG. 4.

FIG. 6 is a schematic cross-sectional view of another portion of thepressure-sensing portion of the pulse wave measuring apparatus shown inFIG. 4.

FIG. 7 is a schematic cross-sectional view of a pressure-sensing portionbased on a variation of the pulse wave measuring apparatus in Embodiment1 of the present invention.

FIG. 8 is a schematic cross-sectional view of a pressure-sensing portionof a pulse wave measuring apparatus in Embodiment 2 of the presentinvention.

FIG. 9 is a schematic cross-sectional view of a pressure-sensing portionof a pulse wave measuring apparatus in Embodiment 3 of the presentinvention.

FIG. 10 is an enlarged cross-sectional view of the pressure-sensingportion of the pulse wave measuring apparatus shown in FIG. 9.

FIG. 11 is a schematic perspective view of a semiconductor substrate ofthe pulse wave measuring apparatus in Embodiment 3 of the presentinvention.

FIG. 12 is a schematic cross-sectional view of a pressure-sensingportion of a pulse wave measuring apparatus in Embodiment 4 of thepresent invention.

FIG. 13 is an enlarged cross-sectional view of the pressure-sensingportion of the pulse wave measuring apparatus shown in FIG. 12.

FIG. 14 is a schematic perspective view of a semiconductor substrate ofthe pulse wave measuring apparatus in Embodiment 4 of the presentinvention.

FIG. 15 is a schematic cross-sectional view of a pressure-sensingportion of a pulse wave measuring apparatus in Embodiment 5 of thepresent invention.

FIG. 16 is a schematic cross-sectional view of a pressure-sensingportion of a pulse wave measuring apparatus in Embodiment 6 of thepresent invention.

FIG. 17 is an enlarged cross-sectional view of the pressure-sensingportion of the pulse wave measuring apparatus shown in FIG. 16.

FIG. 18 is a schematic cross-sectional view of a pressure-sensingportion of a pulse wave measuring apparatus in Embodiment 7 of thepresent invention.

FIG. 19 is an enlarged cross-sectional view of the pressure-sensingportion of the pulse wave measuring apparatus shown in FIG. 18.

FIG. 20 is a schematic cross-sectional view of a pressure-sensingportion of a pulse wave measuring apparatus in Embodiment 8 of thepresent invention.

FIG. 21 is a schematic perspective view of a pressure-sensing portion ofa pulse wave measuring apparatus in Embodiment 9 of the presentinvention.

FIG. 22 is a schematic perspective view illustrating a state in which aprotection film for the pressure-sensing portion of the pulse wavemeasuring apparatus shown in FIG. 21 is removed.

FIG. 23 is a schematic cross-sectional view of the pressure-sensingportion of the pulse wave measuring apparatus shown in FIG. 21.

FIG. 24 is an enlarged cross-sectional view of a region XXIV shown inFIG. 23.

FIG. 25 is an exploded perspective view illustrating an assemblystructure of the pressure-sensing portion of the pulse wave measuringapparatus shown in FIG. 21.

FIG. 26 is a schematic diagram illustrating a method of measuring anoutput characteristic of a pressure-sensing device in the pulse wavemeasuring apparatus shown in FIG. 21.

FIG. 27 is a schematic perspective view illustrating a state in which aprotection film is removed, showing a variation of the pulse wavemeasuring apparatus in Embodiment 9 of the present invention.

FIG. 28 is a schematic cross-sectional view of a pressure-sensingportion of a pulse wave measuring apparatus in Embodiment 10 of thepresent invention.

FIG. 29 is a schematic diagram illustrating a method of connecting thepressure-sensing portion shown in FIG. 28 to a circuit board.

FIG. 30 is a plan view of a connector portion of a flexible line shownin FIG. 29.

FIG. 31 is a schematic cross-sectional view of a pressure-sensingportion of a pulse wave measuring apparatus in Embodiment 11 of thepresent invention.

FIG. 32 is a schematic cross-sectional view of a pressure-sensingportion of a pulse wave measuring apparatus in Embodiment 12 of thepresent invention.

FIG. 33 is a schematic cross-sectional view of a pressure-sensingportion of a conventional pulse wave measuring apparatus.

FIG. 34 is a schematic diagram for pointing out a problem in theconventional pulse wave measuring apparatus.

BEST MODES FOR CARRYING OUT THE INVENTION

In the following, embodiments of the present invention will be describedwith reference to the figures.

Embodiment 1

A pulse wave measuring apparatus in Embodiment 1 of the presentinvention adopts a semiconductor substrate as a substrate and adopts apressure-sensing device formed on the main surface of the semiconductorsubstrate as the pressure-sensing means. The pulse wave measuringapparatus adopts a pressure-sensing device utilizing a diaphragm, forexample. The pulse wave measuring apparatus in the present embodiment isa pressurization-type pulse wave measuring apparatus for measuring thepulse wave by pressing the main surface of the semiconductor substrateagainst the body surface.

(Overall Structure)

Referring first to FIGS. 1, 2A and 2B, an overall structure of the pulsewave measuring apparatus in Embodiment 1 according to the presentinvention will be described. FIG. 1 is a schematic perspective viewshowing the overall structure of the pulse wave measuring apparatus inEmbodiment 1 of the present invention. FIG. 2A is a schematicperspective view of a structure of a housing portion of the pulse wavemeasuring apparatus in the present embodiment, and FIG. 2B is a bottomview of the housing portion.

As shown in FIG. 1, the pulse wave measuring apparatus in the presentembodiment includes a securing base 34, a housing portion 28, and a band36. Securing base 34 serves to fix a measurement site of a living body40 of the subject. In the pulse wave measuring apparatus shown in FIG.1, a wrist of the subject is adopted as the measurement site subjectedto measurement of the pulse wave. Therefore, securing base 34 is shapedso as to be able to fix the wrist.

Band 36 is attached to a prescribed position of securing base 34. Inaddition, housing portion 28 is attached to band 36. Housing portion 28has a pressure-sensing portion 30 (see FIGS. 2A and 2B) on its lowersurface as will be described later. Therefore, by winding band 36 aroundthe wrist placed on securing base 34, pressure-sensing portion 30 ofhousing portion 28 is located on the measurement site of the subject.

As shown in FIGS. 2A and 2B, pressure-sensing portion 30 including apressure-sensing surface 2 is arranged on the lower surface side ofhousing portion 28. An air bag 32 for pressing pressure-sensing portion30 against the living body is attached to pressure-sensing portion 30.Here, pressure-sensing portion 30 is supported in a manner movable in anup-down direction.

(Pressurization Mechanism)

Referring now to FIGS. 3A and 3B, a pressurization mechanism in thepulse wave measuring apparatus in the present embodiment will bedescribed. FIGS. 3A and 3B are schematic diagrams showing thepressurization mechanism of the pulse wave measuring apparatus in thepresent embodiment. FIG. 3A is a schematic diagram illustrating a statebefore measurement, and FIG. 3B is a schematic diagram illustrating astate during measurement.

As shown in FIGS. 3A and 3B, a circuit board 26 is arranged insidehousing portion 28 of the pulse wave measuring apparatus. A processingcircuit processing a signal output from the pressure-sensing device isformed on circuit board 26. In transmission of the signal output fromthe pressure-sensing device, a flexible line 18 is used. Flexible line18 has one end electrically connected to pressure-sensing portion 30having the pressure-sensing device, and the other end electricallyconnected to circuit board 26.

As shown in FIG. 3A, before measurement, pressure-sensing portion 30 isarranged in a position distant from body surface 40. Here, flexible line18 has an excessive portion, and is loosened between pressure-sensingportion 30 and circuit board 26. During measurement, as the not-shownair bag expands, pressure-sensing portion 30 is moved in the directionshown with arrow A as shown in FIG. 3B, and pressure-sensing surface 2of the pressure-sensing portion 30 is pressed against body surface 40.In such a state, the pulse wave produced in the artery located directlyunder the skin, that is, body surface 40, can be detected using thepressure-sensing device.

(Structure of Pressure-Sensing Portion)

A structure of the pressure-sensing portion of the pulse wave measuringapparatus in the present embodiment will now be described in detail.FIG. 4 is a schematic cross-sectional view of the pulse wave measuringapparatus in the present embodiment, and FIG. 5 is an enlargedcross-sectional view of the pressure-sensing portion shown in FIG. 4.FIG. 6 is a schematic cross-sectional view of another portion of thepressure-sensing portion of the pulse wave measuring apparatus shown inFIG. 4.

As shown in FIGS. 4 and 5, pressure-sensing portion 30 mainly includessemiconductor substrate 1 having the pressure-sensing device formed onthe main surface, support member 9 supporting a back surface ofsemiconductor substrate 1, protection member 12 holding support member 9and protecting semiconductor substrate 1, flexible line 18 electricallyconnected to semiconductor substrate 1, and protection film 16 attachedto a contact portion with the body surface of pressure-sensing portion30.

Protection member 12 is fabricated with a resin member having asubstantially trapezoidal shape, and has an accommodation spaceaccommodating semiconductor substrate 1 in its surface. In the presentembodiment, the accommodation space is formed by a concave portionformed in the surface of protection member 12; On the bottom surface ofthe concave portion, support member 9 is disposed. Support member 9 is aplate-shaped member attaining a function as an insulating member, and aglass plate or an anodized aluminum plate is used as support member 9,for example. Semiconductor substrate 1 is adhered to the upper surfaceof support member 9. Adhesion is carried out by anodic bonding, forexample.

As shown in FIG. 4, protection member 12 has a communication hole 13 forintroducing atmosphere formed. Communication hole 13 reaches the lowersurface of support member 9 arranged in the concave portion ofprotection member 12. Support member 9 has a communication hole 10formed. Communication hole 10 communicates to communication hole 13provided in protection member 12 described above, and reaches the lowersurface of semiconductor substrate 1 arranged on support member 9. Asmall hole 7 is provided in a prescribed region of the lower surface ofsemiconductor substrate 1, and communicates to communication hole 10provided in support member 9 described above. A diaphragm which is aportion of the pressure-sensing device is formed in an upper portion ofsmall hole 7. In this manner, communication holes 13, 10 and small hole7 are provided so as to introduce atmosphere therethrough, so that thelower surface of the diaphragm is maintained to an atmospheric pressure.

As shown in FIG. 5, flexible line 18 has one end brazed to a connectionelectrode portion 5 a provided on the main surface of semiconductorsubstrate 1 by a brazing material 24, and has the other end electricallyconnected a not-shown circuit board. The flexible line is implemented bycoating and supporting a plurality of foil-like wires with a flexiblesheet, and generally referred to as a flexible flat cable. Flexible line18 is drawn out from the end portion of semiconductor substrate 1 towardthe side surface of protection member 12, and fixed to protection member12 by an adhesive 25.

Here, flexible line 18 includes a fixed portion 18 a fixed to protectionmember 12 by adhesive 25, a connection portion 18 b connected tosemiconductor substrate 1 by brazing material 24, and a loosened portion18 c located between fixed portion 18 a and connection portion 18 b andarranged in a slightly loosened manner. By providing loosened portion 18c, loosened portion 18 c mitigates the stress even when volumefluctuation occurs in flexible line 18, and direct application of thestress to semiconductor substrate 1 is avoided.

(Structure of Air Chamber)

As shown in FIG. 5, a wall surface 20 a of the concave portion formingthe accommodation space of protection member 12 is arranged such that anair chamber 20 is interposed between the wall surface and the endsurface of semiconductor substrate 1. In other words, wall surface 20 aof protection member 12 and the end surface of semiconductor substrate 1are arranged spaced apart from each other, so as to form air chamber 20.In the present embodiment, air chamber 20 is provided around the entireperimeter of semiconductor substrate 1.

As shown in FIG. 6, air chamber 20 is open to the atmosphere through acommunication hole 14 provided in protection member 12. In this manner,the air in air chamber 20 is constantly maintained to the atmosphericpressure. In the pulse wave measuring apparatus in the presentembodiment, the end surface of support member 9 is also structured toface air chamber 20.

(Function and Effect)

As described above, in the pulse wave measuring apparatus in the presentembodiment, the end surface of the semiconductor substrate having thepressure-sensing device formed on the main surface is surrounded by theair chamber. Accordingly, as compared with the pulse wave measuringapparatus in which another member is arranged on the end surface of thesemiconductor substrate, the stress is not applied to the semiconductorsubstrate even when variation in the ambient temperature or heattransfer from the body surface takes place. Therefore, accurate andstable measurement of the pulse wave is allowed.

In addition, by covering the end surface of the semiconductor substratewith the air chamber, deformation of the semiconductor substrate in thelateral direction caused by pressurization of the semiconductorsubstrate against the body surface is no longer suppressed. Accordingly,application of the stress from the end surface of the semiconductorsubstrate to the substrate is avoided. Consequently, accurate and stablemeasurement of the pulse wave is allowed.

Moreover, as the semiconductor substrate is disposed in the concaveportion serving as the accommodation space of the protection member,protection of the semiconductor substrate by the protection member isensured. Therefore, a compact and high-performance pulse wave measuringapparatus can be provided.

FIG. 7 is a schematic cross-sectional view of the pressure-sensingportion based on a variation of the pulse wave measuring apparatus inthe present embodiment. As shown in FIG. 6, the structure in whichflexible line 18 includes loosened portion 18 c in order to avoidapplication of the stress from flexible line 18 to semiconductorsubstrate 1 has been described by way of example. As shown in FIG. 7,however, a portion 18 d having rigidity different from that of anotherportion may be formed between fixed portion 18 a and connection portion18 b of flexible line 18. Examples of a method of forming portion 18 dhaving rigidity different from that of another portion include a methodof partially removing a coating of flexible line 18 so as to expose theline, and a method of partially reducing a thickness of the coating offlexible line 18.

Embodiment 2

A structure of a pressure-sensing portion of a pulse wave measuringapparatus in Embodiment 2 of the present invention will now be describedin detail. FIG. 8 is a schematic cross-sectional view of thepressure-sensing portion of the pulse wave measuring apparatus inEmbodiment 2 of the present invention. The pulse wave measuringapparatus in the present embodiment adopts a pressure-sensing deviceformed on the main surface of the semiconductor substrate as thepressure-sensing means, as in Embodiment 1 described above. It is notedthat the same reference characters are given to components the same orcorresponding to those in Embodiment 1 described above, and descriptionthereof will not be repeated.

(Structure of Pressure-Sensing Portion)

As shown in FIG. 8, the pulse wave measuring apparatus in the presentembodiment has air chamber 20 formed so as to face the end surface ofsemiconductor substrate 1 as in Embodiment 1 described above. In thepulse wave measuring apparatus in the present embodiment, flexible line18 includes a loosened portion 19 formed by bending the line in a degreelarger than loosened portion 18 c in Embodiment 1 described above,between fixed portion 18 a and connection potion 18 b. Loosened portion19 is arranged in air chamber 20.

(Function and Effect)

As described above, the loosened portion provided in the flexible lineis arranged in the air chamber, so that a larger loosened portion can beprovided. If a larger loosened portion is provided, correspondingly, thestress applied to the semiconductor substrate can further be reduced.Therefore, more accurate and stable measurement of the pulse wave isallowed. In addition, by arranging the loosened portion in the airchamber, a larger size of the apparatus due to provision of the loosenedportion is avoided, whereby a compact and high-performance pulse wavemeasuring apparatus can be provided.

Embodiment 3

A structure of a pulse wave measuring apparatus in Embodiment 3 of thepresent invention will now be described in detail. FIG. 9 is a schematiccross-sectional view of a pressure-sensing portion of the pulse wavemeasuring apparatus in Embodiment 3 of the present invention. FIG. 10 isan enlarged cross-sectional view of the pressure-sensing portion shownin FIG. 9. FIG. 11 is a schematic perspective view of a structure of asemiconductor substrate of the pulse wave measuring apparatus shown inFIG. 9. The pulse wave measuring apparatus in the present embodimentadopts a pressure-sensing device formed on the main surface of thesemiconductor substrate as the pressure-sensing means, as in Embodiment1 described above. It is noted that the same reference characters aregiven to components the same or corresponding to those in Embodiment 1described above, and description thereof will not be repeated.

(Structure of Pressure-Sensing Portion)

As shown in FIGS. 9 and 10, pressure-sensing portion 30 of the pulsewave measuring apparatus in the present embodiment, likewise inEmbodiment 1 described above, mainly includes semiconductor substrate 1having the pressure-sensing device formed on the main surface, supportmember 9 supporting a back surface of semiconductor substrate 1,protection member 12 holding support member 9 and protectingsemiconductor substrate 1, flexible line 18 electrically connected tosemiconductor substrate 1, and protection film 16 attached to a contactportion with the body surface of pressure-sensing portion 30.

In pressure-sensing portion 30 of the pulse wave measuring apparatus inthe present embodiment, protection member 12 is arranged so as to be incontact with the end surface of semiconductor substrate 1. Accordingly,semiconductor substrate 1 is protected by protection member 12.

(Structure of Semiconductor Substrate)

As shown in FIG. 11, semiconductor substrate 1 has a plurality ofpressure-sensing devices 3 on the main surface. The plurality ofpressure-sensing devices 3 are arranged in the vicinity of a centralportion of semiconductor substrate 1. In a prescribed region of the mainsurface of semiconductor substrate 1, an interconnection 5 formed of aconductor film for transmitting a signal output from pressure-sensingdevice 3 to the outside is formed. Interconnection 5 is connected toconnection electrode portion 5 a also formed of a conductor film. Oneend of flexible line 18 is brazed to connection electrode portion 5 ausing brazing material 24 (see FIG. 10).

A groove 4 is provided on the main surface of semiconductor substrate 1so as to surround pressure-sensing device 3. Groove 4 implements a thinportion along the perimeter of semiconductor substrate 1. Insemiconductor substrate 1 shown in FIG. 11, groove 4 is provided alongthree sides of semiconductor substrate 1, and the thin portions extendin three directions of pressure-sensing device 3.

(Function and Effect)

As described above, in the pulse wave measuring apparatus in the presentembodiment, the groove is formed so as to surround the pressure-sensingdevice on the main surface of the semiconductor substrate, and thegroove implements the thin portion. Therefore, even when volumefluctuation of the protection member takes place due to variation in theambient temperature or heat transfer from the body surface, the stressapplied from the protection member to the semiconductor substrate ismitigated by the thin portion, and accurate and stable measurement ofthe pulse wave is allowed.

In addition, by providing the thin portion on the main surface of thesemiconductor substrate, deformation of the semiconductor substrate inthe lateral direction caused by pressurization of the semiconductorsubstrate against the body surface is less likely to be restricted, andthe stress applied from the end surface of the semiconductor substrateto the substrate is mitigated by the thin portion. Consequently,accurate and stable measurement of the pulse wave is allowed.

Moreover, in the present embodiment, the stress is mitigated by such asimple structure as the groove in the semiconductor substrate.Therefore, a compact and high-performance pulse wave measuring apparatuscan be provided.

As shown in FIG. 10, in the present embodiment, similarly to Embodiment1 described above, flexible line 18 includes loosened portion 18 c inorder to avoid application of the stress from flexible line 18 tosemiconductor substrate 1. Alternatively, a portion having rigiditydifferent from that of another portion may be formed between fixedportion 18 a and connection portion 18 b of flexible line 18.

Embodiment 4

A structure of a pulse wave measuring apparatus in Embodiment 4 of thepresent invention will now be described in detail. FIG. 12 is aschematic cross-sectional view of a pressure-sensing portion of thepulse wave measuring apparatus in Embodiment 4 of the present invention.FIG. 13 is an enlarged cross-sectional view of the pressure-sensingportion shown in FIG. 12. FIG. 14 is a schematic perspective view of astructure of the semiconductor substrate of the pulse wave measuringapparatus shown in FIG. 12. The pulse wave measuring apparatus in thepresent embodiment adopts a pressure-sensing device formed on the mainsurface of the semiconductor substrate as the pressure-sensing means, asin Embodiment 1 described above. It is noted that the same referencecharacters are given to components the same or corresponding to those inEmbodiment 1 described above, and description thereof will not berepeated.

(Structure of Pressure-Sensing Portion)

As shown in FIGS. 12 and 13, pressure-sensing portion 30 of the pulsewave measuring apparatus in the present embodiment, likewise inEmbodiment 1 described above, mainly includes semiconductor substrate 1having the pressure-sensing device formed on the main surface, supportmember 9 supporting a back surface of semiconductor substrate 1,protection member 12 holding support member 9 and protectingsemiconductor substrate 1, flexible line 18 electrically connected tosemiconductor substrate 1, and protection film 16 attached to a contactportion with the body surface of pressure-sensing portion 30.

In pressure-sensing portion 30 of the pulse wave measuring apparatus inthe present embodiment, protection member 12 is arranged so as to be incontact with the end surface of semiconductor substrate 1. Accordingly,semiconductor substrate 1 is protected by protection member 12.

(Structure of Semiconductor Substrate)

As shown in FIG. 14, semiconductor substrate 1 has a plurality ofpressure-sensing devices 3 on the main surface. The plurality ofpressure-sensing devices 3 are arranged in the vicinity of the centralportion of semiconductor substrate 1. In a prescribed region of the mainsurface of semiconductor substrate 1, interconnection 5 formed of aconductor film for transmitting a signal output from pressure-sensingdevice 3 to the outside is formed.

In a prescribed region of semiconductor substrate 1, a stepped-downportion 6 is provided. Stepped-down portion 6 includes a stepped-downsurface lower than pressure-sensing surface 2 serving as the mainsurface of semiconductor substrate 1, and connection electrode portion 5a formed of a conductor film is formed on the stepped-down surface.Connection electrode portion 5 a is connected to interconnection 5described above. One end of flexible line 18 is brazed to connectionelectrode portion 5 a using brazing material 24 (see FIG. 13). Insemiconductor substrate 1 shown in FIG. 13, stepped-down portions 6 areprovided on opposing sides of semiconductor substrate 1.

(Structure in the Vicinity of Connection Electrode Portion)

As shown in FIG. 13, in pressure-sensing portion 30 of the pulse wavemeasuring apparatus in the present embodiment, semiconductor substrate 1including stepped-down portion 6 described above is arranged on supportmember 9. In stepped-down portion 6, flexible line 18 is located onconnection electrode portion 5 a. Here, the upper surface of flexibleline 18 located on a side opposite to connection electrode portion 5 aand the main surface of semiconductor substrate 1 are located on asubstantially identical plane. In other words, a portion being incontact with the lower surface of protection film 16 has a substantiallyflat shape.

(Function and Effect)

As described above, in the pulse wave measuring apparatus in the presentembodiment, the surface of the pressure-sensing portion pressed againstthe body surface has a substantially flat shape, and application of acomponent of force of the skin tension to the semiconductor substrate isavoided. Therefore, accurate and stable measurement of the pulse wave isallowed.

As shown in FIG. 13, in the present embodiment, similarly to Embodiment1 described above, flexible line 18 includes loosened portion 18 c inorder to avoid application of the stress from flexible line 18 tosemiconductor substrate 1. Alternatively, a portion having rigiditydifferent from that of another portion may be formed between fixedportion 18 a and connection portion 18 b of flexible line 18.

Embodiment 5

A structure of a pressure-sensing portion of the pulse wave measuringapparatus in Embodiment 5 of the present invention will now be describedin detail. FIG. 15 is a schematic cross-sectional view of thepressure-sensing portion of the pulse wave measuring apparatus inEmbodiment 5 of the present invention. The pulse wave measuringapparatus in the present embodiment adopts a pressure-sensing deviceformed on the main surface of the semiconductor substrate as thepressure-sensing means, as in Embodiment 4 described above. It is notedthat the same reference characters are given to components the same orcorresponding to those in Embodiment 4 described above, and descriptionthereof will not be repeated.

(Structure of Pressure-Sensing Portion)

As shown in FIG. 15, the pulse wave measuring apparatus in the presentembodiment has a structure implemented by combining Embodiments 2 and 4described above. Specifically, semiconductor substrate 1 hasstepped-down portion 6 on the main surface, and connection electrodeportion 5 a is located on stepped-down portion 6. Flexible line 18 islocated on connection electrode portion 5 a, and the upper surface offlexible line 18 and the main surface of semiconductor substrate 1 arelocated on a substantially identical plane. In addition, air chamber 20is formed so as to face the end surface of semiconductor substrate 1.Loosened portion 19 formed by bending flexible line 18 in a largerdegree is arranged in air chamber 20.

(Function and Effect)

As described above, in the pulse wave measuring apparatus in the presentembodiment, the surface of the pressure-sensing portion pressed againstthe body surface has a substantially flat shape by providing thestepped-down portion in the semiconductor substrate. Accordingly, thepressure-sensing portion is less susceptible to the component of forceof the skin tension. In addition, as the end surface of thesemiconductor substrate is surrounded by the air chamber, the stressapplied to the end surface of the semiconductor substrate issignificantly reduced as compared with the pulse wave measuringapparatus in which another member is arranged on the end surface of thesemiconductor substrate. Moreover, as the loosened portion is providedin the flexible line, application of the stress from the flexible lineto the semiconductor substrate can be avoided. In this manner, a varietyof forces applied to the semiconductor substrate are eliminated, andtherefore, highly accurate and stable measurement of the pulse wave isallowed.

Embodiment 6

A structure of the pulse wave measuring apparatus in Embodiment 6 of thepresent invention will now be described in detail. FIG. 16 is aschematic cross-sectional view of a pressure-sensing portion of thepulse wave measuring apparatus in Embodiment 6 of the present invention.FIG. 17 is an enlarged cross-sectional view of the pressure-sensingportion shown in FIG. 16. The pulse wave measuring apparatus in thepresent embodiment adopts a pressure-sensing device formed on the mainsurface of the semiconductor substrate as the pressure-sensing means, asin Embodiment 4 described above. It is noted that the same referencecharacters are given to components the same or corresponding to those inEmbodiment 4 described above, and description thereof will not berepeated.

(Structure of Pressure-Sensing Portion)

As shown in FIGS. 16 and 17, in the pulse wave measuring apparatus inthe present embodiment, a height of the step provided in semiconductorsubstrate 1 is larger than that in the pulse wave measuring apparatus inEmbodiment 4 described above. Flexible line 18 is arranged on connectionelectrode portion 5 a on stepped-down portion 6. In addition, a spacermember 22 is arranged on flexible line 18. Here, the upper surface ofspacer member 22 located on a side opposite to flexible line 18 and themain surface of semiconductor substrate 1 are located on a substantiallyidentical plane. In other words, a portion being in contact with thelower surface of protection film 16 has a substantially flat shape.

(Function and Effect)

As described above, in the pulse wave measuring apparatus in the presentembodiment, the surface of the pressure-sensing portion pressed againstthe body surface has a substantially flat shape by employing the spacermember, and application of the component of force of the skin tension tothe semiconductor substrate can be avoided. Therefore, accurate andstable measurement of the pulse wave is allowed.

Embodiment 7

A structure of the pulse wave measuring apparatus in Embodiment 7 of thepresent invention will now be described in detail. FIG. 18 is aschematic cross-sectional view of a pressure-sensing portion of thepulse wave measuring apparatus in Embodiment 7 of the present invention.FIG. 19 is an enlarged cross-sectional view of the pressure-sensingportion shown in FIG. 18. The pulse wave measuring apparatus in thepresent embodiment adopts a pressure-sensing device formed on the mainsurface of the semiconductor substrate as the pressure-sensing means, asin Embodiment 1 described above. It is noted that the same referencecharacters are given to components the same or corresponding to those inEmbodiment 1 described above, and description thereof will not berepeated.

(Structure of Pressure-Sensing Portion)

As shown in FIGS. 18 and 19, pressure-sensing portion 30 of the pulsewave measuring apparatus in the present embodiment, likewise inEmbodiment 1 described above, mainly includes semiconductor substrate 1having the pressure-sensing device formed on the main surface, supportmember 9 supporting a back surface of semiconductor substrate 1,protection member 12 holding support member 9 and protectingsemiconductor substrate 1, flexible line 18 electrically connected tosemiconductor substrate 1, and protection film 16 attached to a contactportion with the body surface of pressure-sensing portion 30.

In pressure-sensing portion 30 of the pulse wave measuring apparatus inthe present embodiment, protection member 12 is arranged so as to be incontact with the end surface of semiconductor substrate 1. Accordingly,semiconductor substrate 1 is protected by protection member 12.

(Structure of Semiconductor Substrate)

As shown in FIGS. 18 and 19, in a prescribed region of the main surfaceof semiconductor substrate 1, interconnection 5 formed of a conductorfilm for transmitting a signal output from pressure-sensing device 3 tothe outside is formed. Interconnection 5 is connected to connectionelectrode portion 5 a provided on the back surface of semiconductorsubstrate 1 through a connection contact 8 provided in semiconductorsubstrate 1. In other words, connection electrode portion 5 a is formedin a position lower than the main surface of semiconductor substrate 1.Connection contact 8 is implemented as a plug formed by filling athrough hole provided in semiconductor substrate 1 with a conductivemember.

Support member 9 has a notch 11 in a position corresponding toconnection electrode portion 5 a provided on the back surface ofsemiconductor substrate 1. As such, one end of flexible line 18 can beconnected to connection electrode portion 5 a, and flexible line 18 isbrazed to connection electrode portion 5 a with brazing material 24 onthe back surface of semiconductor substrate 1. Here, flexible line 18 isdrawn out of the side surface of protection member 12 through aninsertion hole 15 provided in protection member 12.

(Function and Effect)

As described above, in the pulse wave measuring apparatus of the presentembodiment, by providing the connection electrode portion on the backsurface of the semiconductor substrate, the flexible line is not locatedon the main surface of the semiconductor substrate. Accordingly, thesurface of the pressure-sensing portion pressed against the body surfacehas a substantially flat shape, and application of the component offorce of the skin tension to the semiconductor substrate can be avoided.Therefore, accurate and stable measurement of the pulse wave is allowed.

As shown in FIG. 19, in the present embodiment, similarly to Embodiment1 described above, flexible line 18 includes loosened portion 18 c inorder to avoid application of the stress from flexible line 18 tosemiconductor substrate 1. Alternatively, a portion having rigiditydifferent from that of another portion may be formed between fixedportion 18 a and connection portion 18 b of flexible line 18.

Embodiment 8

A structure of a pressure-sensing portion of the pulse wave measuringapparatus in Embodiment 8 of the present invention will now be describedin detail. FIG. 20 is a schematic cross-sectional view of thepressure-sensing portion of the pulse wave measuring apparatus inEmbodiment 8 of the present invention. The pulse wave measuringapparatus in the present embodiment adopts a pressure-sensing deviceformed on the main surface of the semiconductor substrate as thepressure-sensing means, as in Embodiment 7 described above. It is notedthat the same reference characters are given to components the same orcorresponding to those in Embodiment 7 described above, and descriptionthereof will not be repeated.

(Structure of Pressure-Sensing Portion)

As shown in FIG. 20, the pulse wave measuring apparatus in the presentembodiment has a structure implemented by combining Embodiments 2 and 7described above. Specifically, semiconductor substrate 1 has connectioncontact 8 formed by filling the through hole with the conductive member,and has connection electrode portion 5 a on the back surface. Flexibleline 18 is connected to connection electrode portion 5 a. In addition,air chamber 20 is formed so as to face the end surface of semiconductorsubstrate 1. Loosened portion 19 formed by bending flexible line 18 in alarger degree is arranged in air chamber 20.

(Function and Effect)

As described above, in the pulse wave measuring apparatus of the presentembodiment, by providing the connection electrode portion on the backsurface of the semiconductor substrate, the flexible line is not locatedon the main surface of the semiconductor substrate. Accordingly, thesurface of the pressure-sensing portion pressed against the body surfacehas a substantially flat shape, and application of the component offorce of the skin tension to the semiconductor substrate can be avoided.As the end surface of the semiconductor substrate is surrounded by theair chamber, the stress applied to the end surface of the semiconductorsubstrate is significantly reduced as compared with the pulse wavemeasuring apparatus in which another member is arranged on the endsurface of the semiconductor substrate. Moreover, as the loosenedportion is provided in the flexible line, application of the stress fromthe flexible line to the semiconductor substrate can also be avoided. Inthis manner, a variety of forces applied to the semiconductor substrateare eliminated, and therefore, highly accurate and stable measurement ofthe pulse wave is allowed.

(Further Problems of Pulse Wave Measuring Apparatus Shown in Embodiments1 to 8)

In the pulse wave measuring apparatus having the structure shown inEmbodiments 1 to 8 described above, a variety of forces applied to theend portion of the semiconductor substrate can be eliminated, anddrastic improvement in measurement accuracy can effectively be achievedas compared with the conventional pulse wave measuring apparatus. On theother hand, further improvement is still required in the followingpoints.

First, when the pulse wave measuring apparatus is repeatedly used, theprotection film attached to the protection member so as to cover thepressure-sensing surface may detach. This is because the flexible lineis bent by repeated elevation and lowering of the pressure-sensingportion and it comes off from a sidewall of the protection member due tothe pressurization force from the protection film.

Secondly, accurate measurement of output characteristics of thepressure-sensing device is difficult in an inspection process beforeproduct shipment carried out in order to grasp variation in the outputcharacteristics of the pressure-sensing device. As described above, whenthe pressure-sensing device formed on the main surface of thesemiconductor substrate is used as the pressure-sensing means, outputcharacteristics of individual sensor chips may be different from oneanother due to fluctuation in manufacturing conditions or the like.Accordingly, for highly accurate measurement of the pulse wave, it isnecessary to grasp the output characteristics of the individual sensorchips as well as to correct a measurement value as required. Here,measurement of the output characteristics of the pressure-sensing deviceis carried out, for example, by arranging a pressure-sensing portion inthe sealed system, increasing a pressure in the system so as to apply aprescribed pressure to the pressure-sensing surface, and measuring anoutput. In the pulse wave measuring apparatus having the structure shownin Embodiments 1 to 8 described above, however, it is difficult toimplement the sealed system due to a structural problem, and toaccurately measure the output characteristics.

Thirdly, there is a possibility of disconnection of the flexible line atthe end portion of the semiconductor substrate. In the pulse wavemeasuring apparatus shown in Embodiments 7 and 8 described above, theconnection electrode portion connected to the flexible line is providedon the back surface of the semiconductor substrate. Accordingly,application of the pressurization force produced by pressing thepressure-sensing portion against the living body to the flexible line isavoided, and consequently, disconnection of the flexible line isunlikely. In the pulse wave measuring apparatus shown in Embodiments 1to 6 described above, however, the connection electrode portionconnected to the flexible line is located on the main surface side ofthe semiconductor substrate. Then, the flexible line is provided on themain surface of the semiconductor substrate, and accordingly, thepressurization force produced by pressing the pressure-sensing portionagainst the living body concentrates on a portion of the flexible linelocated at the end portion of the semiconductor substrate, resulting indisconnection. In particular, when the air chamber is provided aroundthe semiconductor substrate as in the pulse wave measuring apparatusshown in Embodiments 1, 2 and 5, the stress may concentrate not only onthe portion of the flexible line located at the end portion of thesemiconductor substrate but also on a portion of the flexible linelocated at the end portion of the protection member, due to introductionof the skin in the air chamber at the time of pressurization. In such acase, disconnection of the flexible line is further likely.

Fourthly, there is a problem of susceptibility to static electricity ornoise from electric or magnetic field. In the pulse wave measuringapparatus shown in Embodiments 1 to 8 described above, the main surfaceof the semiconductor substrate is merely covered with a thin protectionfilm. Therefore, such a pulse wave measuring apparatus is susceptible tostatic electricity or noise from electric or magnetic field, andaccurate measurement of the pulse wave cannot be carried out under suchan external influence.

Fifthly, there remains a problem of safety. During measurement, acurrent flows in the pressure-sensing device and the temperature of thesemiconductor substrate is slightly increased. Though such temperatureincrease is less likely to cause a problem under a room temperature, apossibility of cold burn cannot be denied if measurement is performedunder a high temperature.

In the following, a pulse wave measuring apparatus overcoming thesevarious problems by further improving the pulse wave measuringapparatuses in Embodiments 1 to 8 described above will be described indetail with reference to the drawings.

Embodiment 9

Initially, a structure of the pulse wave measuring apparatus inEmbodiment 9 of the present invention will be described in detail. FIG.21 is a schematic perspective view of a pressure-sensing portion of thepulse wave measuring apparatus in Embodiment 9 of the present invention.FIG. 22 is a schematic perspective view illustrating a state in whichthe protection film for the pressure-sensing portion shown in FIG. 21 isremoved. FIG. 23 is a schematic cross-sectional view of thepressure-sensing portion shown in FIG. 21. FIG. 24 is an enlargedcross-sectional view of a region XXIV shown in FIG. 23. The pulse wavemeasuring apparatus in the present embodiment adopts a pressure-sensingdevice formed on the main surface of the semiconductor substrate as thepressure-sensing means, as in Embodiment 1 described above. It is notedthat the same reference characters are given to components the same orcorresponding to those in Embodiment 1 described above, and descriptionthereof will not be repeated.

(Structure of Pressure-Sensing Portion)

As shown in FIGS. 21 to 23, pressure-sensing portion 30 of the pulsewave measuring apparatus in the present embodiment mainly includessemiconductor substrate 1 having the pressure-sensing device formed onthe main surface, support member 9 supporting a back surface ofsemiconductor substrate 1, protection member 12 holding support member 9and protecting semiconductor substrate 1, flexible line 18 electricallyconnected to semiconductor substrate 1, and protection film 16 attachedto a contact portion with the body surface of pressure-sensing portion30.

Protection member 12 includes a base portion 44 serving as an innerframe body containing the accommodation space and a cap portion 46serving as an outer frame body fitted to base portion 44 so as toenclose an outer wall thereof. In other words, protection member 12 isdivided into base portion 44 and cap portion 46.

Base portion 44 is shaped like a substantially rectangularparallelepiped, and has an accommodation space accommodatingsemiconductor substrate 1 and support member 9 in its upper portion. Theaccommodation space is formed by a concave portion provided in an uppersurface of base portion 44. Cap portion 46 is formed such that its outershape viewed from a direction orthogonal to the main surface ofsemiconductor substrate 1 disposed in the accommodation space issubstantially circular. A concave fitting portion 47 fitting to theinner portion of O ring 42 serving as attachment means described lateris provided in an outer circumferential wall of cap portion 46. Concavefitting portion 47 is located on the entire circumference of cap portion46. A screw hole is provided on a lower surface of base portion 44 andcap portion 46. By attaching a screw 50 with an attachment plate 48being interposed, base portion 44 and cap portion 46 are fixed.

In pressure-sensing portion 30 of the pulse wave measuring apparatus inthe present embodiment, flexible line 18 having one end attached to theend portion of the main surface of semiconductor substrate 1 is insertedbetween base portion 44 and cap portion 46, and drawn out from the lowersurface of pressure-sensing portion 30. Therefore, even after repeateduse, coming off of the flexible line and detachment of protection film16 is unlikely.

In addition, as shown in FIG. 24, cap portion 46 has an overhangingportion 46 a facing, with a distance, a perimeter of the upper surfaceserving as an accommodation space forming surface of base portion 44.Overhanging portion 46 a is provided so as to project from an innersurface of cap portion 46. Overhanging portion 46 a is provided so as tocover a prescribed portion of flexible line 18 inserted between baseportion 44 and cap portion 46 from above, and serves to protect flexibleline 18 when pressure-sensing portion 30 is pressed against the livingbody.

In the present embodiment, a distance d1 between the end portion ofsemiconductor substrate 1 and the inner surface of cap portion 46 isadjusted to 1.4 mm, and a distance d2 between the end portion ofsemiconductor substrate 1 and a tip end of overhanging portion 46 a isadjusted to approximately 0.8 mm. By setting distance d2 to not largerthan 1.0 mm as above, introduction of the skin in air chamber 20 whenpressure-sensing portion 30 is pressed against the living body will beless likely. Accordingly, concentration on flexible line 18 of thepressurization force produced by pressing pressure-sensing portion 30against the living body is avoided, and disconnection of flexible line18 is prevented.

As shown in FIGS. 21 and 23, protection film 16 is attached to capportion 46 so as to cover the main surface of semiconductor substrate 1and air chamber 20 located at the end portion of semiconductor substrate1. Here, the peripheral portion of protection film 16 covers the outercircumferential wall of cap portion 46. By fitting the inner portion ofO ring 42 around concave fitting portion 47 provided in the outercircumferential wall of cap portion 46 over protection film 16,protection film 16 is fastened and attached to cap portion 46. The outerportion of O ring 42 fitted to cap portion 46 is located outside concavefitting portion 47, and projects from the outer circumferential wall ofcap portion 46. Here, protection film 16 is formed with a flexiblemember such as silicon rubber, and has a collar portion 16 a extendingin four directions provided in its peripheral portion. A cut portion 16b is provided between collar portions 16 a.

As described above, protection film 16 is fixed by O ring 42, so thatprotection film 20 is unlikely to detach from cap portion 46 even afterrepeated use. In addition, O ring 42 is fitted to concave fittingportion 47 so that detachment of protection film 16 is further unlikely.Accordingly, a pulse wave measuring apparatus less likely to break afterrepeated use can be obtained.

In pressure-sensing portion 30 of the pulse wave measuring apparatus inthe present embodiment, base portion 42 serving as the inner frame bodyand cap portion 44 serving as the outer frame body are formed with aceramic material. If base portion 42 and cap portion 44 are formed withthe ceramic material which is a material attaining high thermalconductivity, heat produced by current flow in the pressure-sensingdevice provided in semiconductor substrate 1 is effectively dissipatedby base portion 42 and cap portion 44 through support member 9, whichleads to suppression of temperature increase on the surface ofpressure-sensing portion 30. Therefore, a pulse wave measuring apparatusless likely to cause cold burn and excellent in safety can be provided.

(Assembly Procedure)

FIG. 25 is an exploded perspective view illustrating an assemblyprocedure of the pressure-sensing portion of the pulse wave measuringapparatus shown in FIG. 21. In the following, the assembly procedure ofthe pressure-sensing portion of the pulse wave measuring apparatus willbe described with reference to FIG. 25.

First, support member 9 is joined to the back surface side ofsemiconductor substrate 1 having the flexible line (not shown) attached,by anodic bonding or the like. Successively, semiconductor substrate 1joined to support member 9 is accommodated in the accommodation spaceprovided in the upper portion of base portion 44, and fixed using anadhesive or the like.

Concurrently, protection film 16 covers cap portion 46, and is fixed tocap portion 46 by means of the O ring. Here, by grasping collar portion16 a provided in the peripheral portion of protection film 16, capportion 46 can be covered with protection film 16 with excellentworkability. In addition, as cut portion 16 b is provided between collarportions 16 a, workability is further improved.

Thereafter, cap portion 46 having protection film 16 attached is fittedto base portion 44 having semiconductor substrate 1 assembled. Then,attachment plate 48 is attached from below using screw 50. Here, theflexible line is drawn out of a slit provided in attachment plate 48.

As described above, assembly of pressure-sensing portion 30 as shown inFIG. 21 is completed. According to the pulse wave measuring apparatushaving the structure described above, pressure-sensing portion 30 can beassembled with a very simple operation, and manufacturing cost cansignificantly be reduced.

(Method of Measuring Output Characteristic)

FIG. 26 is a schematic diagram illustrating a method of measuring anoutput characteristic of the pressure-sensing device in the pulse wavemeasuring apparatus in the present embodiment. In the pressure-sensingportion in the pulse wave measuring apparatus in the present embodiment,protection film 16 is fixed to cap portion 46 by means of O ring 42 asdescribed above. By adopting such a structure, accurate and facilitatedmeasurement of the output characteristic of the pressure-sensing devicein the inspection process before product shipment can be carried out. Ameasurement method will be described in the following.

As shown in FIG. 26, a measurement jig 52 of a cylindrical shape with abottom is prepared as a jig for measuring the output characteristic ofthe pressure-sensing device. Measurement jig 52 has a pressurizationchamber 53 inside. Pressurization chamber 53 is connected to apressurization pump 55, so that it can be pressurized by drivingpressurization pump 55. An opening of measurement jig 52 is made so asto be larger than an outer shape of cap portion 46 of pressure-sensingportion 30 and so as to have an outer diameter equal to or slightlysmaller than that of the O ring described above.

In order to measure the output characteristic of the pressure-sensingdevice formed in semiconductor substrate 1, it is necessary to uniformlyapply a pressure on the entire surface of pressure-sensing surface 2serving as the main surface of semiconductor substrate 1 as well as tomonitor an output obtained from the pressure-sensing device. In thepulse wave measuring apparatus in the present embodiment, measurement ofthe output characteristic of the pressure-sensing device is carried outin such a manner that pressure-sensing portion 30 is covered withmeasurement jig 52 from above, the opening of measurement jig 52 is madeto be in intimate contact with O ring 42, the pressure in pressurizationchamber 53 is increased while maintaining the above-described state, andthe output from the pressure-sensing device is monitored. By adoptingsuch a method, the pressure by compressed air (a force shown with anarrow C in the figure) can uniformly be applied to the entire surface ofpressure-sensing surface 2, so that accurate and rapid measurement ofthe output characteristic of the pressure-sensing device can beachieved.

(Function and Effect)

As described above, by adopting the structure of the pressure-sensingportion as in the present embodiment, in addition to achieving theeffect in Embodiment 1 described above, a pulse wave measuring apparatusfree from disconnection of the flexible line and excellent in safety, inwhich the protection film is less likely to detach and the outputcharacteristic of the pressure-sensing device is accurately and rapidlymeasured can be obtained. Therefore, a pulse wave measuring apparatusovercoming a variety of problems described above can be provided.

(Variation)

FIG. 27 is a schematic perspective view illustrating a state in which aprotection film is removed, showing a variation of the pulse wavemeasuring apparatus in the present embodiment. As shown in FIG. 27,small irregularities are provided on an outer surface of cap portion 46,so that heat produced in semiconductor substrate 1 can furthereffectively be dissipated. Such irregularities are readily formed, forexample, by providing a plurality of concave portions 46 b on the outersurface of cap portion 46 as shown in FIG. 27. With such a structure, asurface area of cap portion 46 is increased, and heat dissipationperformance is improved.

Embodiment 10

A structure of the pulse wave measuring apparatus in Embodiment 10 ofthe present invention will now be described in detail. FIG. 28 is aschematic cross-sectional view of a pressure-sensing portion of thepulse wave measuring apparatus in Embodiment 10 of the presentinvention. FIG. 29 is a schematic diagram illustrating a method ofconnection of the pressure-sensing portion shown in FIG. 28 to thecircuit board. FIG. 30 is a plan view of a connector portion of theflexible line shown in FIG. 29. The pulse wave measuring apparatus inthe present embodiment adopts a pressure-sensing device formed on themain surface of the semiconductor substrate as the pressure-sensingmeans, as in Embodiment 9 described above. It is noted that the samereference characters are given to components the same or correspondingto those in Embodiment 9 described above, and description thereof willnot be repeated.

(Structure of Pressure-Sensing Portion)

As shown in FIG. 28, pressure-sensing portion 30 of the pulse wavemeasuring apparatus in the present embodiment mainly includessemiconductor substrate 1 having the pressure-sensing device formed onthe main surface, support member 9 supporting a back surface ofsemiconductor substrate 1, protection member 12 holding support member 9and protecting semiconductor substrate 1, a flexible line 18Aelectrically connected to semiconductor substrate 1, a flexible line 18Belectrically connected to protection member 12, and protection film 16attached to a contact portion with the body surface of pressure-sensingportion 30.

Protection member 12, likewise in the pulse wave measuring apparatusshown in Embodiment 9 described above, includes base portion 44 servingas the inner frame body containing the accommodation space and capportion 46 serving as the outer frame body fitted to base portion 44 soas to enclose the outer wall thereof. Base portion 44 and cap portion 46are fixed by attachment plate 48 from below. The pulse wave measuringapparatus in the present embodiment, however, is different from thepulse wave measuring apparatus shown in Embodiment 9 described above inthat base portion 44 and cap portion 46 are both formed of zinc which isa conductive material. In the pulse wave measuring apparatus in thepresent embodiment, base portion 44 and cap portion 46 are formed ofzinc, considering formability and thermal conductivity. Meanwhile, anyconductive material may be used for forming base portion 44 and capportion 46, and noble metals (such as gold, silver, platinum, or thelike), copper, aluminum, or the like may be employed, for example.

Pressure-sensing portion 30 of the pulse wave measuring apparatus in thepresent embodiment includes flexible line 18B having one end attached tocap portion 46 and attachment plate 48, in addition to flexible line 18Ahaving one end attached to the end portion of semiconductor substrate 1.One end of flexible line 18B is clamped, for example, by cap portion 46and attachment plate 48, so that flexible line 18B is electricallyconnected to cap portion 46 and attachment plate 48. Here, as attachmentplate 48 abuts on base portion 44, base portion 44 is also electricallyconnected to flexible line 18B.

As shown in FIG. 29, connectors 60 are attached to flexible lines 18Aand 18B drawn out of pressure-sensing portion 30 respectively. Thoughflexible lines 18A and 18B may be implemented by separate flexiblelines, in the pulse wave measuring apparatus in the present embodiment,one flexible line is shared from a viewpoint of reduction in the numberof parts and facilitated assembly operation. Specifically, flexible line18 is connected such that one end thereof is electrically connected tothe end portion of semiconductor substrate 1 and the other end thereofis electrically connected to cap portion 46 and attachment plate 48, andconnector 60 is provided in a midpoint of flexible line 18.

As shown in FIG. 29, connector 60 provided in flexible line 18 isinserted in a socket 64 for establishing connection to circuit board 26.As shown in FIG. 30, flexible line 18 extending from the end portionattached to semiconductor substrate 1 includes a signal line 18A1 forthe pressure-sensing device provided in semiconductor substrate 1, whichis electrically connected to a connection pin 62 a of connector 60. Onthe other hand, flexible line 18B extending from the end portionattached to cap portion 46 and attachment plate 48 is provided with aground line 18B1, which is electrically connected to a connection pin 62b of connector 60. Ground line 18B 1 is electrically connected to aninterconnection set to a ground potential and provided in circuit board26, while connector 60 is attached to socket 64.

(Function and Effect)

According to the structure as described above, base portion 44 and capportion 46 are connected to the ground, so that base portion 44 and capportion 46 serve as a lightning rod and electromagnetic shielding forthe pressure-sensing device formed in semiconductor substrate 1.Accordingly, the pressure-sensing device is less susceptible to staticelectricity or noise from electric or magnetic field, and accurate andstable measurement of the pulse wave is allowed. According to the pulsewave measuring apparatus as in the present embodiment, a pulse wavemeasuring apparatus attaining excellent resistance to static electricityand noise from electric or magnetic field in addition to attaining theeffect in Embodiment 9 described above can be obtained. In addition, asa conductive material generally has superior thermal conductivity, heatproduced in semiconductor substrate 1 can effectively be dissipated tobase portion 42 and cap portion 44.

If flexible line 18A having signal line 18A1 formed and flexible line18B1 having ground line 18B1 formed are bundled by bringing them closerto each other such that ground line 18B1 faces signal line 18A1,superposition of the noise on the signal output from thepressure-sensing device is prevented, thereby attaining further accuratemeasurement of the pulse wave.

Embodiment 11

A structure of the pulse wave measuring apparatus in Embodiment 11 ofthe present invention will now be described in detail. FIG. 31 is aschematic cross-sectional view of a pressure-sensing portion of thepulse wave measuring apparatus in Embodiment 11 of the presentinvention. The pulse wave measuring apparatus in the present embodimentadopts a pressure-sensing device formed on the main surface of thesemiconductor substrate as the pressure-sensing means, as in Embodiment9 described above. It is noted that the same reference characters aregiven to components the same or corresponding to those in Embodiment 9described above, and description thereof will not be repeated.

(Structure of Pressure-Sensing Portion)

The pulse wave measuring apparatus in the present embodiment isimplemented by integrally forming protection film 16 and O ring 42 inthe pulse wave measuring apparatus in Embodiment 9 described above.Specifically, as shown in FIG. 31, a projected fitting portion 16 dprojecting toward inside and a projected portion 16 c projecting towardoutside are provided in a portion of protection film 16 facing the outercircumferential wall of cap portion 46, so as to integrally formprotection film 16 and O ring 42 in Embodiment 9 described above.

Projected fitting portion 16 d is provided in an area of protection film16 around its entire periphery. Projected fitting portion 16 d is fittedto concave fitting portion 47 provided on the outer circumferential wallof cap portion 46, so as to attach protection film 16 to cap portion 46.In other words, projected fitting portion 16 d corresponds to the innerportion of O ring 42 in the pulse wave measuring apparatus shown inEmbodiment 9 described above. Projected portion 16 c is provided in anarea of protection film 16 around its entire periphery, and serves as aportion being in intimate contact with the opening of the measurementjig used in measurement of the output characteristic of thepressure-sensing device in Embodiment 9 described above. That is,projected portion 16 c corresponds to the outer portion of O ring 42 inthe pulse wave measuring apparatus shown in Embodiment 9 describedabove.

(Function and Effect)

According to the structure as above, a pulse wave measuring apparatusattaining facilitated assembly operation and reduction in manufacturingcost in addition to attaining the effect in Embodiment 9 described abovecan be obtained.

Embodiment 12

A structure of the pulse wave measuring apparatus in Embodiment 12 ofthe present invention will now be described in detail. FIG. 32 is aschematic cross-sectional view of a pressure-sensing portion of a pulsewave measuring apparatus in Embodiment 12 of the present invention. Thepulse wave measuring apparatus in the present embodiment adopts apressure-sensing device formed on the main surface of the semiconductorsubstrate as the pressure-sensing means, as in Embodiment 9 describedabove. It is noted that the same reference characters are given tocomponents the same or corresponding to those in Embodiment 9 describedabove, and description thereof will not be repeated.

(Structure of Pressure-Sensing Portion)

The pulse wave measuring apparatus in the present embodiment isimplemented by integrally forming protection film 16, O ring 42, and capportion 46 in the pulse wave measuring apparatus in Embodiment 9described above. Specifically, as shown in FIG. 32, a protection filmportion 46 d covering semiconductor substrate 1 and air chamber 20 isprovided in the upper portion of cap portion 46, and a projected portion46 c projecting toward outside on the outer circumferential wall of capportion 46 is provided, so as to integrally form protection film 16, Oring 42, and cap portion 46 in Embodiment 9 described above.

Projected portion 46 c described above is provided on the entire outercircumferential wall of cap portion 46, and serves as a portion being inintimate contact with the opening of the measurement jig used inmeasurement of the output characteristic of the pressure-sensing devicein Embodiment 9 described above. That is, projected portion 46 ccorresponds to the outer portion of O ring 42 in the pulse wavemeasuring apparatus shown in Embodiment 9 described above.

(Function and Effect)

According to the structure as above, a pulse wave measuring apparatusattaining facilitated assembly operation and reduction in manufacturingcost in addition to attaining the effect in Embodiment 9 described abovecan be obtained. In addition, as the number of parts is further reducedas compared with the pulse wave measuring apparatus shown in Embodiment11 described above, the assembly operation is further facilitated, andsignificant reduction in the manufacturing cost is achieved.

(Other Variation)

In Embodiments 1 to 12 described above, though an example adopting apressure-sensing device including a diaphragm as pressure-sensing meanshas been explained, the pressure-sensing means is not particularlylimited thereto. For example, a strain gauge may be employed as thepressure-sensing means.

In addition, in Embodiments 1 to 12 described above, though an examplein which the accommodation space accommodating the substrate is formedby providing a concave portion in the protection member has beenexplained, the accommodation space is not particularly limited thereto.

Moreover, in Embodiments 9 to 12 described above, though description hasbeen provided on the basis of the pulse wave measuring apparatus havingthe air chamber formed at the end portion of the semiconductorsubstrate, such a basis is not essential. That is, any combination ofthe techniques disclosed in Embodiments 1 to 12 is possible, and anysuitable combination can be adopted as necessary in accordance withconditions of use or the like.

Furthermore, though a pulse wave measuring apparatus measuring a pulsewave has exemplarily been described in Embodiments 1 to 12 as above, thepresent invention is applicable to any apparatus for measuring a contactpressure with respect to the body surface by pressurization against thebody surface, such as an ocular tension measuring apparatus.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

INDUSTRIAL APPLICABILITY

The present invention is utilized in a pressurization-type pulse wavemeasuring apparatus measuring data of a living body in a non-invasivemanner in order to know medical condition of a subject.

1. A pulse wave measuring apparatus for measuring a pulse wave whenpressed against a living body, comprising: a substrate having a pressuresensor on a main surface; and a protection member having anaccommodation space accommodating said substrate; wherein saidprotection member is formed of a conductive material and a wall surfaceof said protection member forming said accommodation space is arrangedsuch that an air chamber is interposed between said wall surface and anend surface of said substrate.
 2. The pulse wave measuring apparatusaccording to claim 1, wherein said air chamber is provided around anentire perimeter of said substrate.
 3. The pulse wave measuringapparatus according to claim 1, wherein said air chamber is open toatmosphere.
 4. The pulse wave measuring apparatus according to claim 1,further comprising a circuit board processing a signal, and a flexibleline transmitting a signal output from said pressure sensor to saidcircuit board, wherein said flexible line includes a fixed portion fixedto said protection member, a connection portion connected to saidsubstrate, and a loose portion located between said fixed portion andsaid connection portion.
 5. The pulse wave measuring apparatus accordingto claim 4, wherein said loosened portion is located inside said airchamber.
 6. The pulse wave measuring apparatus according to claim 1,further comprising a circuit board processing a signal, and a flexibleline transmitting a signal output from said pressure sensor to saidcircuit board, wherein said flexible line includes a fixed portion fixedto said protection member and a connection portion connected to saidsubstrate, and a portion having rigidity different from that of anotherportion of said flexible line is located between said fixed portion andsaid connection portion of said flexible line.
 7. The pulse wavemeasuring apparatus according to claim 1, further comprising aprotection film covering said main surface of said substrate and saidair chamber, and an attachment mechanism configured for fastening aperipheral portion of said protection film to an outer circumferentialwall of said protection member for attachment.
 8. The pulse wavemeasuring apparatus according to claim 7, wherein said protection memberhas a substantially circular outer shape when viewed from a directionorthogonal to said main surface of said substrate, and said attachmentmechanism is an O ring.
 9. The pulse wave measuring apparatus accordingto claim 8, wherein said outer circumferential wall of said protectionmember has a concave fittings portion fitting to an inner portion ofsaid O ring on an entire circumference, and an outer portion of said Oring projects from said outer circumferential wall of said protectionmember.
 10. The pulse wave measuring apparatus according to claim 7,wherein said protection film and said attachment mechanism areintegrally formed.
 11. The pulse wave measuring apparatus according toclaim 7, wherein said protection film has a collar portion in saidperipheral portion.
 12. The pulse wave measuring apparatus according toclaim 1, wherein said protection member includes an inner frame bodycontaining said accommodation space and an outer frame body fitted tosaid inner frame body so as to enclose an outer wall of said inner framebody, said outer frame body has a protection film portion covering saidmain surface of said substrate and said air chamber, and an outercircumferential wall of said outer frame body has a projected portion onits entire circumference.
 13. The pulse wave measuring apparatusaccording to claim 1, further comprising a circuit board processing asignal, and a flexible line transmitting a signal output from saidpressure sensor to said circuit board, wherein said protection memberincludes an inner frame body containing said accommodation space and anouter frame body fitted to said inner frame body so as to enclose anouter wall of said inner frame body, and said flexible line is insertedbetween said inner frame body and said outer flame body.
 14. The pulsewave measuring apparatus according to claim 13, wherein said outer framebody has an overhanging portion projecting from an inner surface of saidouter frame body and facing, at a distance, a perimeter of anaccommodation space forming surface of said inner frame body where saidaccommodation space is formed, and said flexible line inserted betweensaid inner frame body and said outer frame body is protected by saidoverhanging portion.
 15. (canceled)
 16. The pulse wave measuringapparatus according to claim 1, wherein said protection member iselectrically connected to a ground potential.
 17. The pulse wavemeasuring apparatus according to claim 16, further comprising a circuitboard processing a signal, and a flexible line transmitting a signaloutput from said pressure sensor to said circuit board, wherein saidprotection member is electrically connected to the ground potential bysaid flexible line.
 18. The pulse wave measuring apparatus according toclaim 1, wherein said protection member is formed of a metal material ora ceramic material.
 19. The pulse wave measuring apparatus according toclaim 1, wherein said protection member has a plurality of smallirregularities on its surface. 20-29. (canceled)